Superstorm Sandy was pushing the Hudson River over its bank, across the lawn and parking lot at the plant, and to his office’s front door. The unleashed Hudson was on its way to filling up underground rooms and tunnels — some as big as a gymnasium, bending steel doors and bringing a 21st-century wastewater treatment plant practically to its knees.

“I’ve been here for 35 years. I’ve never seen anything like it,” he said Thursday morning, just hours short of the month anniversary of Sandy roaring ashore in the Northeast.

On the other end of the phone that night was Con Edison, listening to Beckett’s request to cut the plant’s electricity as the floodwaters rose. That decision prevented total catastrophic damage and protected workers.

The storm, though, still took a toll on the county’s largest wastewater treatment plant, which serves a swath of Westchester stretching from Mount Kisco to Eastchester to Yonkers. The Department of Environmental Facilities is asking Westchester lawmakers for $14.5 million to pay for repairs there and to several ancillary sewage facilities across the county. Most of that will be borrowed and some is expected to be reimbursed by the federal government.

“It’s almost all (from) inundation,” Environmental Facilities Commissioner Tom Lauro said of the damage. “This was all due to the surge.”

Lauro met this week with county legislators and ticked off some of the damage, including the complete submersion of four boilers and 250 motors that run mixing pumps at the Yonkers plant. Miles of pipe insulation were soaked and had to be removed. Two 5,000-gallon tanks filled with a sticky thickening agent spilled their contents after being shifted and cracked by the surging Hudson.

Legislator Judy Myers described Lauro’s funding request as “a very large ask.”

“However, this is obviously very necessary,” she said.

The water climbed 25 feet up the walls in some places, flooding cameras and sensors that allowed operators to monitor the sewage-treatment process from the plant’s control room. Some 5,000 feet of temporary lighting strung through the underground warren of rooms and tunnels is still in use.

Immediately after the storm, the county was pumping 120 million gallons a day of partially treated sewage into the Hudson. Lauro estimated that’s down to about 80,000 gallons a day. Lab results coming in any day now are expected to show the plant is operating normally and releasing fully treated sewage.

Workers on Thursday were busy wielding power washers and anti-mold detergent to clean the plant’s interior. Others were checking wiring. For now, technicians will climb ladders, read instruments and record their findings on clipboards.

“Our main goal was to get the (sewage-treatment) processes back. Now we’re working on the auxiliary systems,” Beckett said. “We’ll get it back.”